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SubjectRe: mmotm 2020-05-11-15-43 uploaded (mm/memcontrol.c, huge pages)
On Mon, May 11, 2020 at 09:41:24PM -0700, Randy Dunlap wrote:
> On 5/11/20 3:44 PM, Andrew Morton wrote:
> > The mm-of-the-moment snapshot 2020-05-11-15-43 has been uploaded to
> >
> > http://www.ozlabs.org/~akpm/mmotm/
> >
> > mmotm-readme.txt says
> >
> > README for mm-of-the-moment:
> >
> > http://www.ozlabs.org/~akpm/mmotm/
> >
> > This is a snapshot of my -mm patch queue. Uploaded at random hopefully
> > more than once a week.
> >
> > You will need quilt to apply these patches to the latest Linus release (5.x
> > or 5.x-rcY). The series file is in broken-out.tar.gz and is duplicated in
> > http://ozlabs.org/~akpm/mmotm/series
> >
> > The file broken-out.tar.gz contains two datestamp files: .DATE and
> > .DATE-yyyy-mm-dd-hh-mm-ss. Both contain the string yyyy-mm-dd-hh-mm-ss,
> > followed by the base kernel version against which this patch series is to
> > be applied.
> >
> > This tree is partially included in linux-next. To see which patches are
> > included in linux-next, consult the `series' file. Only the patches
> > within the #NEXT_PATCHES_START/#NEXT_PATCHES_END markers are included in
> > linux-next.
> >
> >
> > A full copy of the full kernel tree with the linux-next and mmotm patches
> > already applied is available through git within an hour of the mmotm
> > release. Individual mmotm releases are tagged. The master branch always
> > points to the latest release, so it's constantly rebasing.
> >
> > https://github.com/hnaz/linux-mm
> >
> > The directory http://www.ozlabs.org/~akpm/mmots/ (mm-of-the-second)
> > contains daily snapshots of the -mm tree. It is updated more frequently
> > than mmotm, and is untested.
> >
> > A git copy of this tree is also available at
> >
> > https://github.com/hnaz/linux-mm

Thanks for the report, Randy.

---

Randy reports:

> on x86_64:
>
> In file included from ../arch/x86/include/asm/atomic.h:5:0,
> from ../include/linux/atomic.h:7,
> from ../include/linux/page_counter.h:5,
> from ../mm/memcontrol.c:25:
> ../mm/memcontrol.c: In function ‘memcg_stat_show’:
> ../include/linux/compiler.h:394:38: error: call to ‘__compiletime_assert_383’ declared with attribute error: BUILD_BUG failed
> _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> ^
> ../include/linux/compiler.h:375:4: note: in definition of macro ‘__compiletime_assert’
> prefix ## suffix(); \
> ^~~~~~
> ../include/linux/compiler.h:394:2: note: in expansion of macro ‘_compiletime_assert’
> _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> ^~~~~~~~~~~~~~~~~~~
> ../include/linux/build_bug.h:39:37: note: in expansion of macro ‘compiletime_assert’
> #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
> ^~~~~~~~~~~~~~~~~~
> ../include/linux/build_bug.h:59:21: note: in expansion of macro ‘BUILD_BUG_ON_MSG’
> #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
> ^~~~~~~~~~~~~~~~
> ../include/linux/huge_mm.h:319:28: note: in expansion of macro ‘BUILD_BUG’
> #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })

The THP page size macros are CONFIG_TRANSPARENT_HUGEPAGE only.

We already ifdef most THP-related code in memcg, but not these
particular stats. Memcg used to track the pages as they came in, and
PageTransHuge() + hpage_nr_pages() work when THP is not compiled in.

Switching to native vmstat counters, memcg doesn't see the pages, it
only gets a count of THPs. To translate that to bytes, it has to know
how big the THPs are - and that's only available for CONFIG_THP.

Add the necessary ifdefs. /proc/meminfo, smaps etc. also don't show
the THP counters when the feature is compiled out. The event counts
(THP_FAULT_ALLOC, THP_COLLAPSE_ALLOC) were already conditional also.

Style touchup: HPAGE_PMD_NR * PAGE_SIZE is silly. Use HPAGE_PMD_SIZE.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 738d071ba1ef..47c685088a2c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1401,9 +1401,11 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
(u64)memcg_page_state(memcg, NR_WRITEBACK) *
PAGE_SIZE);

+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
seq_buf_printf(&s, "anon_thp %llu\n",
(u64)memcg_page_state(memcg, NR_ANON_THPS) *
- HPAGE_PMD_NR * PAGE_SIZE);
+ HPAGE_PMD_SIZE);
+#endif

for (i = 0; i < NR_LRU_LISTS; i++)
seq_buf_printf(&s, "%s %llu\n", lru_list_name(i),
@@ -3752,7 +3754,9 @@ static int memcg_numa_stat_show(struct seq_file *m, void *v)
static const unsigned int memcg1_stats[] = {
NR_FILE_PAGES,
NR_ANON_MAPPED,
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
NR_ANON_THPS,
+#endif
NR_SHMEM,
NR_FILE_MAPPED,
NR_FILE_DIRTY,
@@ -3763,7 +3767,9 @@ static const unsigned int memcg1_stats[] = {
static const char *const memcg1_stat_names[] = {
"cache",
"rss",
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
"rss_huge",
+#endif
"shmem",
"mapped_file",
"dirty",
@@ -3794,8 +3800,10 @@ static int memcg_stat_show(struct seq_file *m, void *v)
if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account())
continue;
nr = memcg_page_state_local(memcg, memcg1_stats[i]);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
if (memcg1_stats[i] == NR_ANON_THPS)
nr *= HPAGE_PMD_NR;
+#endif
seq_printf(m, "%s %lu\n", memcg1_stat_names[i], nr * PAGE_SIZE);
}

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